Abstract:
This study uses nonlinear transient dynamic Finite Element analysis to determine the structural response of a Naval waste package subjected to impacts from falling nonlithophysal rocks to assess the potential for a breach of the outer corrosion barrier. To achieve this, a series of high-fidelity simulations were performed using the LS-DYNA V970 software on full three-dimensional Finite Element Representations (FERs) of the rock block and waste package, which were meshed in TrueGrid primarily with 8-node constant-stress brick elements. The FEA model explicitly handled the dynamic impact by including contact between the rock and package and accounted for large plastic deformations by using an elastic-plastic material model with strain hardening for the waste package's Alloy 22 outer barrier. The Finite Element analyses covered 14 impact scenarios by varying the rock's mass, velocity, and orientation (corner, edge, and face drops) to identify the worst-case loading conditions. The FEA results showed that in none of the simulated impacts did the effective plastic strain in the waste package's outer barrier exceed the failure criterion of 0.15, concluding that nonlithophysal rock falls do not threaten the package's structural integrity.
